|Unicorn example, philosophy: the problem is about linguistic expressions for non-existent objects and principles of using these expressions. In logic it comes to the question of whether sentences containing expressions for non-existent objects are true, false, or senseless. See also Pegasus, nonexistence, reference, truth value, truth conditions, assertibility, meaning, sense, truth value gap.|
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We simply cannot say under what circumstances there could be unicorns.
E.g. discovery (of fossils) does not provide a proof of existence of mythical figures.
The discovery that there was actually a detective, would not show that Conan Doyle wrote about this man.
Name und Notwendigkeit Frankfurt 1981
S. A. Kripke
Outline of a Theory of Truth (1975)
Recent Essays on Truth and the Liar Paradox, R. L. Martin (Hg), Oxford/NY 1984